1. Field of the Invention
The present invention relates to a connector including a receptacle and a plug which are engaged with each other to be electrically connected to each other.
2. Description of the Prior Art
A conventional connector including a receptacle and a plug which are engaged with each other to be electrically connected to each other by inserting the plug into an insertion groove formed on the receptacle has a structural problem such that foreign matter easily accumulates between contacts of the receptacle and associated contacts of the plug, i.e., between two opposed arrays of contacts of the receptacle (receptacle contacts), which are arranged on opposed inner walls in the insertion groove of the receptacle, and associated two arrays of contacts of the plug (plug contacts), which are arranged on opposite sides of the plug to be capable of being in contact with the two opposed arrays of receptacle contacts, respectively, thus causing a bad connection between the receptacle and the plug. In such a connector, foreign matter is usually removed by repeatedly plugging and unplugging the plug into and from the receptacle. However, since each receptacle contact and the associated plug contact are in surface contact with each other when the plug is connected to the receptacle, it is difficult to make each receptacle contact and the associated plug contact impose loads on each other in a concentrated manner, and accordingly, such foreign matter cannot be removed efficiently by repeatedly plugging and unplugging the plug into and from the receptacle.
To overcome such a problem, an improved connector has been proposed in which each receptacle contact (socket contact) or each plug contact (header contact) is provided with a resilient contact projecting portion which projects in a direction intersecting an insertion/extraction direction of the plug relative to the insertion groove of the receptacle. The other corresponding plug contact or receptacle contact is provided with a contacting portion which is elongated in the insertion/extraction direction and with which the contact projecting portion is in sliding contact when the plug is plugged and unplugged into and from the insertion groove, and the contacting portion thereof is provided, on a surface with which the contact projecting portion comes in contact, with a recessed portion. This improved connector is disclosed in Japanese Unexamined Patent Publication No. 2004-111081.
In such a connector, when the contact projecting portion of each receptacle contact or each plug contact is engaged in the recessed portion of the other corresponding plug contact or receptacle contact, the contact projecting portion and the recessed portion come in contact with each other at two points, which achieves a higher efficiency of removing foreign matter from the insertion groove than that in the above described conventional case where each receptacle contact and the associated plug contact are in surface contact with each other. However, if the plug and the receptacle are not precisely positioned relative to each other when the plug is plugged into the receptacle, there is a possibility of the contact projecting portion and the recessed portion being in contact with each other at only one point, or there is a possibility of the contact projecting portion not being engaged in the recessed portion. If the contact projecting portion and the recessed portion are in contact with each other at only one point, a sliding contact between the contact projecting portion and the recessed portion occurs only at a single point (on a single line), which tends to be incapable of removing foreign matter thoroughly, so that there is a possibility of the contact resistance between the plug and the receptacle becoming unstable. Moreover, if the contact projecting portion does not slip into the recessed portion but rather slides on a flat surface portion on the contacting portion on which the recessed portion is not formed, foreign matter is not trapped into the recessed portion and merely moves on the flat surface portion by insertion/extraction movements of the plug relative to the insertion groove of the receptacle, and accordingly, such foreign matter cannot be removed to a sufficient degree. Furthermore, miniaturization of such a conventional connector reduces the contact pressure between each contacting portion and the associated contact projecting portion, thus causing instability of the contact resistance between the plug and the receptacle.
If the contact projecting portion is replaced with a flat shaped or a substantially flat shaped contact portion so that each contact portion becomes capable of coming in surface contact with the associated contacting portion, it becomes difficult to make each receptacle contact and the associated plug contact impose loads on each other in a concentrated manner when the plug and the receptacle come in contact with each other, and therefore the efficiency of removing foreign matter decreases.
Foreign matter tends to accumulate in the recessed portion on each contacting portion by repeatedly plugging and unplugging the plug into and from the receptacle. Such accumulated foreign matter makes it difficult for the contact projecting portion to enter the associated recessed portion, and also makes it difficult for newly-removed foreign matter to be trapped into the recessed portion; additionally, the contact resistance between the plug and the receptacle becomes unstable because foreign matter trapped and accumulated in the recessed portion is not removed therefrom. On the other hand, if foreign matter is adhered to the recessed portion before the plug is plugged into the receptacle, such foreign matter tends to get trapped deeply into the recessed portion due to plugging and unplugging the plug into and from the receptacle, which also causes instability of the contact resistance between the plug and the receptacle.